The present invention relates to a portable, hand-held vehicle exhaust analyzer.
Due to government regulations, testing of vehicle exhaust emissions for compliance with minimum standards has become a necessary function for testing facilities and repair garages. Originally, only hydrocarbons and carbon monoxide had to be measured, but stricter standards have added oxygen and carbon dioxide, and still stricter regulations require oxides of nitrogen to be measured as well for compliance with statutory requirements. If a vehicle fails an emission test, it must be repaired. In the repair process, a mechanic must be able to tell whether the repairs have affected the content of the exhaust gas that was at an unacceptable level during the emission test. Therefore, there is a need for a vehicle gas analyzer that can be used by repair technicians to determine whether their repairs have remedied emission test failures.
Large platform engine analyzers were initially developed to measure gases emitted in vehicle exhaust. These platform engine analyzers were large devices that were transported by wheeling them around on a large cart. These large engine analyzers are typically utilized by government agencies to perform actual emission tests on vehicles, but their size and considerable expense make them difficult for smaller repair garages to own.
"Portable " exhaust gas analyzers were subsequently developed to be used for repair purposes. While portable exhaust gas analyzers are smaller than the larger platform analyzers used previously, they still weigh over thirty pounds, and are too large to be held in the hands of a user during operation. The units contain a large heater, since the infrared sensing equipment in these units operates at a temperature greater than ambient temperature. Typically a chopper motor is employed to serve as a zero reference for infrared sensors operating in the analyzers. A large pump is also required to advance high volumes of exhaust gas through the analyzer. These components draw a large amount of power, compelling the implementation of a large power supply within the analyzer, take significant amounts of space, and generate substantial heat, necessitating the use of metal throughout the analyzer and reducing the analyzer's "portability". In addition, it is often difficult to remove and replace the parts of the analyzer, such as filters or the pump, which regularly wear out.
Therefore, there is a need for an improved portable exhaust gas analyzer, such as a hand-held vehicle gas analyzer, which is of a size and weight to be carried easily by a user, while still performing the same functions of sampling and sensing gas content in vehicle exhaust as previous exhaust gas analyzers.